Tillage practices in long-term winter wheat-fallow affect soil fertility

Authors: AULA, LAWRENCE - University Of Nebraska; EASTERLY, AMANDA - University Of Nebraska; Mikha, Maysoon; CREECH, CODY - University Of Nebraska

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2024
Publication Date: 2/14/2024
Citation: Aula, L., Easterly, A.C., Mikha, M.M., Creech, C. 2024. Tillage practices in long-term winter wheat-fallow affect soil fertility. Soil Science Society of America Journal. 88(2):498-509. https://doi.org/10.1002/saj2.20628.
DOI: https://doi.org/10.1002/saj2.20628

Interpretive Summary: Sustainable crop production relies on tillage management strategies that improve soil fertility. We evaluated how undisturbed native sod and three long-term tillage practices, moldboard plow (MP), stubble mulch (SM), and no-till (NT), affected soil fertility on a rotation of winter wheat (Triticum aestivum L.)-fallow. After 42 years with no nutrient additions, soil organic matter, some key nutrients (N, P, and K), and soil pH were all influenced by tillage intensity. Soil organic matter and nutrient levels for no-till were less than for native sod but greater than stubble-mulch or moldboard plow. Sod was used as a benchmark for soil fertility evaluation because of no disturbances and continuous soil cover where the agricultural plots contained a fallow period with no residue input. Changes in SOM and some key nutrients (N, P, and K), and soil pH were influenced by tillage intensity. The temporal changes in soil fertility and nutrient dynamics were almost similar for sod and NT. Whereas the tillage intensity associated with SM and MP decreased soil nutrient concentrations. Overall, this study site is an indication of proper management for land use and nutrient dynamics that can lead toward reduced inputs, decrease nutrient losses from agricultural systems, and enhance economical return.

Technical Abstract: The contribution of tillage practices to enhancing soil fertility levels is a major subject of research among agricultural scholars. The objective of this study was to assess the effect of several decades of tillage under winter wheat (Triticum aestivum L.)-fallow on soil fertility levels associated with each tillage practice – moldboard plow (MP), stubble mulch (SM), and no-till (NT) – relative to native sod. The experiment was established in 1970 as a randomized complete block design with three replications and no fertilizer addition of any form. Soil samples from 0-10 and 10-20 cm depth were collected in 2010 and 2011. Soil samples were analyzed for soil organic matter (SOM), total nitrogen (TN), plant-available phosphorus (P), potassium (K), and soil pH. Benchmarks for these variables used to evaluate temporal changes for each treatment were obtained from previous documents containing data that were sampled in 1982 and 1984 from the same site. In 2010-2011, SOM, TN, P, K, and pH were all influenced by the tillage practices at 0-10 cm (P = 0.05). For SOM, the magnitude of the difference between native sod and NT in 1986 was 28% (10.1 g kg-1) and this increased to 30.6% (18.5 g kg-1) in 2010-2011 with native sod storing more SOM. Over time, NT sustained a high level of SOM with 7.7 g kg-1 more SOM than the initial 38.3 g kg-1 reported in 1986. Nonetheless, SOM was expected to reduce over time with NT and this observation could be a result of fluctuations in SOM that may occur in this system, but with an overall trend of a decrease in SOM. Stubble mulch and NT experienced a reduction of 4 and 5.7 g kg-1 from the level of SOM observed in 1986, respectively. Total N with NT was greater than SM and MP by 56%, but 53% lower than TN under the native sod. In general, soil fertility and nutrient availability at this site supported crop production without fertilizer addition for the last fifty-three years after the initiation of the experiment.